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The Hope Group Home › Products › Compressed Air › Compressed Air Dryers › High Capacity Refrigerated Air Dryers

High Capacity Refrigerated Air Dryers

The Hope Group distributes Kaeser's high capacity dryer (KHD) which is designed to dry compressed air to a safe and manageable dew point. With a capacity of up to 20,000 cfm, the KHD can handle the largest drying applications while protecting downstream equipment from damaging moisture.

Pre-cooling for optimum performance

In the Kaeser design, the pre-cooler – re-heater lowers the temperature of the incoming air. This reduces the horsepower requirement of the refrigeration compressor and saves energy costs. Concurrently, the outgoing cooler air is reheated by the incoming warm air. Reheating the air eliminates downstream pipe sweating.

Minimum pressure drop

KHD models feature a pre-cooler – re-heater sized specifically for the application. The shell and tube design includes externally finned, extended surface tubes for significantly more exchanger area than competitive bare tube designs. This results in a smaller package size saving valuable floor space. Kaeser's design incorporates multifunction turbulence enhancer strips. These readily removable devices provide self-cleaning action, which eliminates fouling and minimizes pressure drops. This feature ensures that optimum performance is achieved and maintained long after the dryer is installed and started up.

Direct expansion means consistent dew point

The pre-cooled air enters the refrigerant evaporator where direct expansion of the liquid refrigerant in the tubes further cools the air. Kaeser's direct expansion design provides fast response because the refrigerant evaporates into a gas as it absorbs heat directly from the incoming air. This ensures a consistent dew point downstream.

Quality components for dependability

Kaeser is recognized for its quality design and rugged components:

  • Filtered separator
    Kaeser's filtered separator is located downstream of the evaporator to remove virtually all water droplets and all particles three microns and larger.

  • Three automatic drain traps
    Three automatic drain traps are included in the drain areas where condensate accumulates

  • Manual isolation valves
    Manual isolation valves are included with the automatic drain traps

  • Semi-hermetic refrigerant compressor
    A semi-hermetic refrigerant compressor compresses the low pressure refrigerant gas to a high pressure gas. This proved compressor design ensures a sealed system minimizing the chance for refrigerant leaks.

  • Air or water-cooled condenser
    The gas flows into an air or water cooled condenser where the gaseous refrigerant is cooled by the incoming condenser cooling air or water and is condensed to a liquid.

  • Hot by-pass valve
    A Kaeser hot gas bypass valve accurately maintains a constant suction pressure in the evaporator, stabilizing the dew point.

  • Thermal expansion valve
    The thermal expansion valve meters high pressure liquid refrigerant into the evaporator in response to changes in load. The liquid changes to a low pressure mixture of liquid and vapor after passing through the valve and evaporates while absorbing heat from the compressed air. The gas leaves the evaporator, re-enters the compressor and the cycle is repeated.

Velocity control is the key to uniform cooling

Liquid refrigerant enters the refrigerant evaporator and makes four passes during which it absorbs heat from the air. Concurrently, the liquid evaporates into a low pressure gas. Kaeser's multi-pass configuration provides uniform cooling and stable dew point over a full range of flow conditions. The liquid refrigerant velocity is increased by volume displacement rods inside the tubes. This enhances the heat transfer in the liquid section. Similarly, Kaeser uses turbulence enhancer strips to increase the velocity and disperse the liquid/gas refrigerant mixture to the tube walls where evaporation occurs. On the air side, the heat transfer area is increased by using externally finned, extended surface tubes. By combining velocity, control and increased heat transfer area, Kaeser provides the cooling capability to meet the system's needs.



High Capacity Dryers
With a capacity up to 20,000 cfm, the Kaeser KHD dryer can handle the largest drying applications while protecting downstream equipment from damaging moisture. The KHD model features a pre-cooler/re-heater sized specifically for each customer's requirements.


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